Integrin alpha-IIb/beta-3 (ITGA2B:ITGB3) is a receptor for fibronectin, fibrinogen, plasminogen, prothrombin, thrombospondin and vitronectin. It recognizes the sequence R-G-D in a wide array of ligands. It recognizes the sequence H-H-L-G-G-G-A-K-Q-A-G-D-V in fibrinogen gamma chain (By similarity).

Following activation integrin alpha-IIb/beta-3 brings about platelet/platelet interaction through binding of soluble fibrinogen (PubMed:9111081). This step leads to rapid platelet aggregation which physically plugs ruptured endothelial cell surface (By similarity). Integrin ITGA2B:ITGB3 is also the receptor of erythrocyte-specific ICAM4 ligand involved in heterotypic cell-cell adhesion between erythrocytes and activated platelets (PubMed:12477717)

Heterodimer of an alpha and a beta subunit. The alpha subunit is composed of a heavy and a light chain linked by a disulfide bond. Alpha-IIb associates with beta-3.

Directly interacts with RNF181. Interacts (via C-terminus cytoplasmic tail region) with CIB1; the interaction is direct and calcium-dependent. Interacts (via C-terminus cytoplasmic tail region) with CIB2, CIB3 and CIB4; the interactions are stabilized/increased in a calcium and magnesium-dependent manner.

ITGA2B:ITGB3 interacts with PPIA/CYPA; the interaction is ROS and PPIase activity-dependent and is increased in the presence of thrombin (By similarity). ITGA2B:ITGB3 interacts with SELP (via C-type lectin domain); the interaction mediates cell-cell interaction and adhesion (PubMed:37184585)

Isoform 1 and isoform 2 are expressed in platelets and megakaryocytes, but not in reticulocytes. Not detected in Jurkat, nor in U937 cell lines (PubMed:2351656). Isoform 3 is expressed in prostate adenocarcinoma, as well as in several erythroleukemia, prostate adenocarcinoma and melanoma cell lines, including PC-3, DU-145, HEL, WM983A, WM983B and WM35.

Not detected in platelets, nor in normal prostate (at protein level) (PubMed:9809974)

• Fetomaternal alloimmune thrombocytopenia 2 (FMAIT2)

  A form of fetomaternal alloimmune thrombocytopenia, a bleeding disorder caused by maternal/fetal incompatibility for platelet alloantigens and arising when a fetus inherits a paternal platelet alloantigen that the mother does not possess. During pregnancy, as well as parturition, maternal alloantibodies against paternally-inherited platelet antigens cause destruction of fetal platelets and fetal/neonatal thrombocytopenia. Disease severity and clinical features in the fetus or neonate are heterogeneous.

  While most fetuses remain asymptomatic, others develop skin bleedings (petechiae) or internal organ bleedings. The most severe symptom is intracranial hemorrhage that is mostly discovered postnatally and can result in neurological complications or even death. Mothers with circulating platelet alloantibodies may experience miscarriage.

  FMAIT2 transmission pattern is consistent with autosomal dominant paternal inheritance.

• Glanzmann thrombasthenia 1 (GT1)

  A form of Glanzmann thrombasthenia, a disorder characterized by failure of platelet aggregation, absent or diminished clot retraction, and mucocutaneous bleeding of mild-to-moderate severity. Glanzmann thrombasthenia has been classified into clinical types I and II. In type I, platelets show absence of glycoprotein IIb-IIIa complexes at their surface and lack fibrinogen and clot retraction capability.

  In type II, the platelets express glycoprotein IIb-IIIa complexes at reduced levels, have detectable amounts of fibrinogen, and have low or moderate clot retraction capability. GT1 inheritance is autosomal recessive.

• Bleeding disorder, platelet-type, 16 (BDPLT16)

  An autosomal dominant form of congenital macrothrombocytopenia associated with platelet anisocytosis. It is a disorder of platelet production. Affected individuals may have no or only mildly increased bleeding tendency.

  In vitro studies show mild platelet functional abnormalities.